The assignee of the present invention manufactures and deploys spacecraft for, inter alia, communications and broadcast services. Market demands for such spacecraft have imposed increasingly stringent requirements on spacecraft payloads in response to which large unfurlable reflectors and narrow RF beams are desirable. In such spacecraft, antenna pointing errors less than 0.03° are desirable.
RF autotracking (RFAT) is a technique for reducing antenna pointing errors by steering antenna reflectors mounted to a spacecraft platform to compensate for payload pointing disturbances. U.S. Pat. No. 5,940,034, entitled “Dual RF Autotrack Control”, U.S. Pat. No. 6,570,535, entitled “Single-Receiver Multiple-Antenna RF Autotrack Control”, and U.S. Pat. No. 8,179,313, entitled “Antenna Tracking Profile Estimation” assigned to the assignee of the present invention and incorporated by reference into the present disclosure in their entireties, relate to RFAT techniques.
In the absence of the presently disclosed techniques, nominal pointing accuracy for a large unfurlable reflector may be within about 0.035° in the absence of transients induced by thruster firing (for stationkeeping purposes, for example) and within about 0.065° during thruster induced transients.